In gas turbine engines, bearing-supported high speed rotating shafts are subject to rotor vibrations, which vibrations can be transmitted outwardly to the engine casing. As engine vibration is generally undesirable, various approaches have been used in an attempt to reduce the vibrations transmitted to the engine casing. Such efforts include squeeze film oil dampers, which provide a thin cushion of oil to the outer race of the bearing to damp out vibrations, and hence decrease transmission to the engine case. Oil film damping adds considerable weight, complexity and hence, cost, to the bearing assembly, however, due to the associated hardware required and the modifications required to the oil system of the engine.
Accordingly, there is a need to provide an improved solution to the control of engine vibration.